1. Field of the Invention
The present invention relates to a control device for a hybrid vehicle that has an engine and an electric motor mounted thereon as power sources, the device making it possible to select between an electric travel mode (EV mode), in which traveling is performed using the electric motor only, and a hybrid travel mode (HEV mode), in which traveling is performed using the electric motor and the engine.
2. Background Information
Conventionally known hybrid vehicles of such description include the type disclosed in Japanese Laid-Open Patent Application No. 2002-139136, in which an engine, which is one of the power sources, is decouplably drive-coupled to a wheel by a continuously variable transmission and a clutch, and an electric motor, which is the other power source, is permanently coupled to the wheel.
In this hybrid vehicle, when the accelerator pedal is released and the vehicle speed is equal to or less than a predetermined vehicle speed, stopping the engine and releasing the clutch make it possible to perform regenerative travel (EV travel) in EV mode in which only the electric motor is used. Releasing the clutch as described above during EV travel decouples the engine in a stopped state (as well as the transmission, if present) from the wheels and prevents the engine (transmission) from being dragged (caused to co-rotate) during regenerative travel in EV mode, making it possible to prevent the corresponding energy loss and improve energy efficiency.